Abstract
Using the impact-parameter method, the process He*(21P)+Ar to He+Ar*+e- is investigated theoretically. Particular attention is paid to the anisotropic interaction potential between the excited He and Ar atoms. The results are compared with previous simple straight-line-trajectory calculations. The cross section is found to be affected by the two parts of the potential, the short-range repulsive part and the long-range attractive part. In the low-energy region, the effect of the attractive potential exceeds that of the repulsive one and the ionization cross section exceeds that of the straight-line-trajectory calculations. On the other hand, in the relatively high-energy region, the cross section is found to be smaller than that of the straight-line calculations due to the effect of the repulsive core.